note to moderator - this is MY response to MY own posting. How can this be a duplicate.
success. ADE 4.0 is to be avoided. It crashed after my solution.
The solution is trash the activation.dat preference file.
Navigate to /Users//Library/Application Support/Adobe/Digital Editions and drag the activation.dat file to the trash.
If you are using 10.7, see Access hidden library files | Mac OS 10.7 and later.
I reinstalled ADE 3.0 and life is good.
The Error getting License. License Server Communication Problem: E_ACT_NOT_READY
I just moved from a MacBook Air to MacBook Pro with Yosemite and I can't get it to work either. I uninstalled the .dat file, I uninstall 4.0, I reinstall 3.0 and I can get books to open up in Adobe Digital Editions but if I try to transfer them to my Nook it crashes. Over and over and over.
Sorry to hear that.
I actually was so excited to get the file into ADE (after so many failed attempts) that I never tried to copy it into my nook. You got me worried.
I tried it and it works. So something else is going on with your system. Mine works on a mac mini running 10.10.2. ADE is at 3.0.86137.
my epub books are from OVERDRIVE FWIW.